Field of the Invention
The invention relates to a device for crushing feed material and a grinding tool for use in such a device.
Description of the Background Art
Such devices are known among other things as whirlwind mills for fine grinding and pulverizing of bulk feed material and in particular for grinding heat-sensitive feed. DE 35 43 370 A1, which corresponds to U.S. Pat. No. 4,747,550, discloses such a mill with a cylindrical stator containing a revolving rotor. While the stator extends over the entire axial length of the rotor, the rotor is divided into several grinding steps by arranging axially spaced circular discs. Each grinding step is associated with a plurality of grinding plates which are detachably fastened to the outer circumference of the circular discs. When the rotor is rotating, the grinding plates generate a vortex field with their axially extending edges in which the feed particles are constantly accelerated and deflected. The comminution of the feed material is carried out by acceleration, impact and frictional forces, which the feed particles are subjected to in the vortex field.
A comparatively enhanced mill is described in DE 197 23 705 C1. There, the grinding zone is divided into an inlet-side area where the feed material is first crushed by the mechanical action of the milling strips before it enters the outlet-side region of the grinding zone, where an autogenous comminution takes place in the vortex field of the rotor. In this way, the mill can be adjusted to the specific characteristics of the feed material and the milling process, both in the inlet-side and in the outlet-side milling area by means of design measures, thereby increasing the effectiveness of the mill.